1. Field of the Invention
The present invention relates to a pattern image generation device for an image processing system which includes an image data conversion table and performs processings such as conversion processing, edit processing and the like on color separated image data input before outputting the image data.
2. Description of the Related Art
In a conventional digital copying machine, an analog signal obtained by reading a document is converted into multivalued digital data, the digital data is processed in its granularity, gradation property, fineness and other image quality adjustment, and then the data is recorded and reproduced by means of dot images. In particular, due to the fact that the digitally converted multivalued data is processed, the conventional digital copying machine is able not only to process the image data used to generate a highly fine and highly reproducible image but also to easily carry out various kinds of correction and editing using memory by means of the image data.
Also, in a full color digital copying machine, a document is read optically and is thus color separated to thereby produce read signals B (Blue), G (Green) and R (Red); and, the read signals B (Blue), G (Green) and R are corrected and converted into the record signals Y (Yellow), M (Magenta) and C (Cyanogen) of color materials such as a toner, ink, an ink doner film and the like. Basically, dot images respectively obtained from the respective color materials are output in such a manner that they are superimposed on one another, thereby reproducing a full color document. In this case, images obtained from color materials equal in amount to one another provides an achromatic color and, therefore, actually, an under color removal (UCR) processing is performed to thereby remove the record signals Y, M and C corresponding to the color materials equal in amount so as to avoid the useless consumption of the color materials. However, if the UCR processing is performed, then the amounts of the color materials used are decreased to thereby reduce the depth or graveness of the color, so that mass of the whole color image becomes insufficient. Also, due to the fact that reproduction of grey or black is contrary to reproduction of a highly chromatic color, a simple UCR processing is not able to enhance the reproducibility of the color sufficiently. In order to make up for such massive shortage in the chromatic colors or in order to execute a grey output, black or India ink (K) is generated according to the amount of the color material to be UCR processed. Now, an example of conventional digital color image forming device which is disclosed in Published Unexamined Japanese Patent Application No. Hei-2-70173, will be described hereinafter briefly.
In FIG. 8, there is shown a block diagram of the structure of a digital color image forming device.
In FIG. 8, IIT (image input terminal) 100 is used to read a document by use of a CCD line sensor and color separate the document into read signals B, G and R and also to convert the read signals B, G and R into digital image data. IOT (image output terminal) 115 is used to expose and develop by use of a laser beam and reproduce a color image. Parts interposed between IIT 100 and IOT 115 and including an END conversion module 101 to an IOT interface 110 cooperate in constituting an image data edit processing system (IPS: image processing system). The IPS converts the read signals B, G and R into the toner record signals Y, M, C, and K, and selects and outputs every develop cycle the record signal that corresponds to the develop color. What is important here is, in converting the read signals (B, G and R signals) into the record signals (Y, M, C and K signals), how the balance of the color is adjusted, how the color is reproduced in accordance with the reading characteristics of the IIT and the output characteristics of the IOT, how the balance of the density or contrast of the color is adjusted, how the edge is emphasized or how unsharpness or moire is adjusted, and the like.
IIT 100 takes in 1 pixel in a size of 16 dots/mm with respect to each of the read signals B, G and R by use of a CCD sensor, and outputs the data in 24 bits (3 colors .times.8 bits; 256 gradations). The CCD sensor includes B, G and R filters mounted to the upper surface thereof, has a density of 15 dots/mm and a length of 300 mm, and scans 16 line/mm at a process speed of 190.5 mm/sec. Thus, the CCD outputs the read signals at a speed of 15 M pixels per sec. substantially for the respective colors. And, IIT 100, by means of logarithmic conversion of analog signals of the pixels of B, G and R, converts the information of reflectance into the information of density and further into digital signals.
The IPS is a system which is used to input therein the read signals B, G and R from IIT 100, performs various kinds of data processings on the read signals in order to enhance the reproducibility of color, gradation, fineness and the like, selects the record signal of a develop process color from the record signals Y, M, C and K, converts the selected record signal into an on/off signal, and outputs the on/off signal to IOT 115. As shown in FIG. 8, the IPS includes an END conversion (Equivalent Neutral Density conversion) module 101 which adjusts (converts) the record signal into a grey balanced color signal; a color masking module 102 which matrix operates the read signals B, G and R to thereby convert the read signals into the record signals that correspond to the toner amounts of Y, M and C; a document size detection module 103 which detects a document size in pre-scanning and erases (erases the frame of) a platen color in document read scanning; a color conversion module 104 which converts a color specified in a given area in accordance with an area signal input from an area image control module; a UCR processing & black generation module 105 which generates K in a proper amount in order to prevent a color from being made impure and decreases Y, M and C equally in amounts according to the amount of K generated and also which performs a UCR processing on the K signals as well as the record signals Y, M and C in accordance with signals in a mono-color mode and a full color mode and gates the signals that are obtained after such UCR processing; a space filter 106 having a function to recover an unsharp color and a function to remove a moire; a TRC (Tone Reproduction Control) module 107 which performs a density adjustment, a contrast adjustment, a negative-positive reversal, color balance adjustment and other similar processings in order to improve reproducibility; a reduction and enlargement processing module 108 which performs a reduction and enlargement processing in a main scanning direction; a screen generator 109 which converts a gradation toner signal of a process color into a binary on/off toner signal and outputs the binary on/off toner signal; an IOT interface module 110, an area image control module 111 which includes an area generation circuit and a switch matrix; an edit control module which includes an area command memory 112, a color palette video switch circuit 113, a font buffer 114 and the like; and other similar modules.
As described above, in the digital color image forming device which performs various processings such as correction, conversion, editing and other processings on the image data in a multi-stage manner, there is used a pattern generator PG so as to evaluate the reproducibility, fineness and so on of color image as well as to carry out adjustments and trouble shootings. For example, by using a lattice pattern, mis-registration for each of colors can be observed longitudinally and transversely, if any. Also, the reproducibility of Japanese, especially, kanji (Chinese) character can be observed by means of oblique lines and use of longitudinal and transverse patterns permits observation of poor transfer and gradation reproducibility. The pattern generator PG which generates such constant patterns is normally included within the digital color image forming device and, for example, as a table conversion device for converting signals, there is also used an LUT using a RAM.
In the above-mentioned pattern generator, patterns vary according to the applications of the pattern generator and, therefore, there must be prepared the patterns that correspond to the applications thereof. In order words, it is difficult that a generator is specially provided for generation of pasterns and further various patterns are provided easily.